Nanomechanical Quantum Computer Would Use Carbon Nanotubes as Qubits

Physicists at the Technical University of Munich (TUM) experimented with quantum mechanical phenomena and demonstrated that it is possible to store qubit information in the form of vibrations by using extremely small carbon nanotubes.

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Until now most (still experimentally) quantum computer systems are based on electrically charged particles that are held in an "electromagnetic trap." A disadvantage of these systems is that they are very sensitive to electromagnetic interference and therefore need extensive shielding. Thats why it is good news that the new approach by the physicists at TUM, who have found a way for information to be stored and quantum mechanically processed in mechanical vibrations, seems to be working. Since nanomechanical devices are not charged, they are much less sensitive to electrical interference.

The mechanism behind is to use a carbon nanotube like a guitar string by clamping both ends of it so it can be excited to oscillate. The tube then vibrates more than a million time, due its very small size, allowing information to be retained for up to one second. The information can then be written and read optoelectronically.

"Our concept is based on available technology," says Michael Hartmann, head of the Emmy Noether research group Quantum Optics and Quantum Dynamics at TUM. "It could take us a step closer to the realization of a quantum computer."

(Photo : M.J. Hartmann, TUM)Like a guitar string, nanotubes (black) can be clamped and excited to vibrate. An electric field (electrodes: blue) ensures that two of the many possible states can be selectively addressed.